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HomeMy WebLinkAboutDrainage Report 4466 e 11.0 4141 DRAINAGE REPORT .00 FOR INDIAN LAKES SUBDIVISION, PHASE X COLLEGE STATION, TEXAS AWS NOVEMBER 2006 .10 MBESI# 1062-0016 SUBMITTED BY: 111113 McCLURE & BROWNE ENGINEERING/SURVEYING, INC. 1008 Woodcreek Drive,Suite 103 •College Station,Texas 77845 (979)693-3838• Fax:(979)693-2554•Email:McClureBrowne@Verizon.net ASION tiSaN Indian Lakes, Phase X Drainage Report MBES1#1062-0008 SUMMARY This storm drainage report is intended to analyze the drainage infrastructure proposed for the development of the Indian Lakes Subdivision, Phase X. The existing and proposed conditions are included to show how the design will achieve the desired drainage objectives of Brazos County and the City of College Station. GENERAL INFORMATION Area encompassed by this phase: 79.715e acres Anticipated land use: Single family residential Anticipated number of lots: 40 lots Notes on surrounding development: The area surrounding the site is partially developed with existing phases of Indian Lakes to the west,undeveloped phases of Indian Lakes to the north, east and south. FLOOD HAZARD INFORMATION FEMA FIRM Map#: 48041CO215 C Effective Date: July 2, 1992 Comments: No portion of the site is shown to be within the 100-year floodplain, so it is not currently regulated under the National Flood Insurance Program. Applicable Exhibits: A—Excerpt of FEMA FIRM DESCRIPTION OF DRAINAGE SYSTEMS Primary System: The site is wooded with dense undergrowth. Phase X slopes toward several tributaries of Peach Creek. Peach Creek flows to the Navasota River. Secondary System: Runoff from the residential lots will be captured in roadside ditches where it will be conveyed to the natural streams that flow through the site. Corrugated metal pipes will be used as culverts at road crossings. Applicable Exhibits: B-2—Culvert Sizing Drainage Area Map SECONDARY STORM DRAIN DESIGN Design Storm: 10-yr Return Period(Ditches) 100-yr Return Period(Culverts) Design Methodology Hydrology: Rational Formula Software Model: Excel Spreadsheet(Rational Method) Time of Concentration: minimum = 10 min. Runoff Coefficients: 0.40 - Undeveloped area 0.90 - Paved areas Hydraulics: Manning's Equation Software Model: Excel Spreadsheet Manning's N: 0.024 (corrugated metal) Drainage Report Page 1 of 2 Indian Lakes,Phase X Applicable Exhibits: C-1 Rational Formula Drainage Area Calculations D-1 Culvert#1 Analysis D-2 Culvert#2 Analysis D-3 Culvert#3 Analysis D-4 Culvert#4 Analysis E-1 Ditch Capacity Analysis—Tallulah Trail DETENTION REQUIREMENTS Summary: When considered in conjunction with the previous phases and the over-detention provided by Lake Arapaho,the runoff rates are far below pre-development runoff rates at the Point of Confluence shown on Exhibit B-1. Lake Arapaho reduces the peak runoff from the property by approximately 1300 cfs for the 100-year event as noted in the Drainage Report for Phases 2& 5. Therefore, no additional detention is necessary with this phase of the subdivision. Applicable Exhibits: B-1 Overall Drainage Map EROSION AND SEDIMENTATION CONTROLS Control Measures: Silt fence Hydro-mulch seeding Rock Filter Dams Straw Bale Barriers Construction entrance/exit SWPPP: The contractor shall be responsible for establishing and maintaining the SWPPP in accordance with TCEQ requirements. Drainage Report Page 2 of 2 Indian Lakes,Phase X If 2 <--5 J / / Ii ( - —I, -` -\- \� . )`-- �7 ` l {\ �( .�^ / \ -sem__ --7-=----7-7----7-t--- - ____ --_ - '- I ;' r ,s-/ / ( ��L ( -- - ...------/--- 1.----- - / J ..i f 1 �' ) r ``� \\ r ) / ��-� - - 1J r 1 j /� / / tI s t Ic . - -I-- .J ` f 1 1 1 •/. ,� �� fI- ( 2 \J / 2 ri \ < -----'--,,.. I ,___( b_____1..._szi; ,, 'f; I- ./ } -..1 t l �J 44 // 1 -- // —r 0 i rj ( c , , : \_----p :r( 1 __, ,s .,N,,, , ____,,, / „ , _ , , l A , 4; C �-J* ( ? /1s 1� -. ,v,/r ti. 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INC. r�l=PA T 'U'r, TRAIL 1008 Woodcreek Drive,Suite 103 College Station,Texas 77845 1 u LAMS PHASE �/ (979)693.3838 p LlIL/LL�L� L�llL�L7N�7 A r & a Exhibit E-1 DRAINAGE REPORT FOR INDIAN LAKES SUBDIVISION, PHASE IX COLLEGE STATION, TEXAS December 2005 MBESI# 1062-0012 SUBMITTED BY: McCLURE & BROWNE ENGINEERING/SURVEYING, INC. 1008 Woodcreek Drive,Suite 103 •College Station,Texas 77845 (979)693-3838•Fax:(979)693-2554•Email: McClureBrowne@Verizon.net Indian Lakes, Phase IX lu y Drainage Report MBESI#1062-0012 GENERAL INFORMATION Area encompassed by this phase: 15.4 acres Anticipated land use: Single family residential Anticipated number of lots: 42 lots Notes on surrounding development: The area surrounding the site is developed with existing phases of Indian Lakes on all sides. FLOOD HAZARD INFORMATION FEMA FIRM Map#: 48041CO215 C Effective Date: July 2, 1992 Comments: No portion of the site is shown to be within the 100-year floodplain, so it is not currently regulated under the National Flood Insurance Program. Applicable Exhibits: A—Excerpt of FEMA FIRM DESCRIPTION OF DRAINAGE SYSTEMS Primary System: The site is wooded with dense undergrowth. The topography slopes toward Lake Arapaho, which is located on a tributary of Peach Creek. Peach Creek flows to the Navasota River. Secondary System: Runoff from the residential lots will be captured in the streets by curb and gutters. It will then be conveyed to the natural streams by 3-6' flumes proposed with the development. A corrugated metal pipe will be used for the entrance road culvert, but no other underground storm drainage is included in the project. Applicable Exhibits: B—Drainage Area Map SECONDARY STORM DRAIN DESIGN Design Storm: 10-yr Return Period(Streets) ` 2, �TM 100-yr Return Period(Flumes &Culverts) Design Methodology .77!" S ' � ® + l', • xo� Hydrology: Rational Formula(Culverts) jF y - >3i Hydrology: Software Model: Excel Spreadsheet(Rational Method) o �.. ,t` ... Time of Concentration: 10 min. tep��. `L.71 Runoff Coefficient: 0.55 - Residential areas 4 1 EI9 f ".tf ' Hydraulics: Manning's Equation Software Model: Excel Spreadsheet / Manning's N: 0.024 (corrugated metal) !�• (6"^ 0.013 (concrete pavement) 1f0 Applicable Exhibits: C-1 Rational Formula Drainage Area Calculations C-2 Settlement Drive Culvert Analysis C-3 Wastewater Treatment Plant Driveway Culvert Analysis C-4 6' Flume Analysis C-5 Typical Street Capacity Drainage Report Page 1 of 3 Indian Lakes, Phase IX General Note: Detention for Phase IX of Indian Lakes Subdivision is provided by Lake Arapaho, which was constructed with Phase I of the subdivision. The lake and its accompanying outlet works were designed to capture and store runoff from the 390-acre drainage basin above the dam. The table that follows is an excerpt from the Engineering Report for Lake Arapaho prepared by East Texas Engineers, Inc. in September 2002. The Peak Inflow figures are based on post-development runoff rates. It shows that all rainfall events have been analyzed during the design of the lake and provisions made to store and release water at a significantly reduced rate. Flood Peak Inflow Peak 1 Max. Lake _ Outflow Level • Event (cfs) I (cfs) I (feet msl) PMF I 7794 1 3113 264.9 • 48.1% 3750 I 958262.2 • PMF • 100-yr 1 1536 1 201 260.0 • 1 • 50-yr 1 1305 1 153 259.7 25-yr 1100 114 • 259.4 • 10-yr 1 877 • 113259.0 5-yr 660 • 94 258.6 2-yr I 429 57258.3 Note that for all standard design storms (2-yr through 100-yr) the peak outflows are approximately 10-15% of the peak inflow. No pre-development runoff rates were computed with the analysis of the lake, but the report indicates that an SCS Curve number of 82 was assumed for these post-development computations. The large, rural estate lots that are planned for most of the Indian Lakes Subdivision have a very small percentage of impervious cover associated with them, so the SCS Curve number for the pre-development condition would have been only slightly less than the post-development Curve number. This implies that only small increases in runoff rates would be expected between the pre- and post-development scenarios. Phase IX is developed much more densely than other phases, but when considered in conjunction with the overall drainage basin, it does not significantly alter the SCS curve number enough to warrant additional detention. The high capacity for storage that the lake offers will easily offset any small increases in runoff rates resulting from the Phase IX development. EROSION AND SEDIMENTATION CONTROLS Control Measures: Silt fence Hydromulch seeding Rock Filter Dams Straw Bale Barriers Construction entrance/exit SWPPP: The contractor shall be responsible for establishing and maintaining the SWPPP in accordance with TCEQ requirements. Drainage Report Page 2 of 3 Indian Lakes, Phase IX SUMMARY Indian Lakes Subdivision, Phase IX is a subdivision for single-family residences on lots that are approximately 0.25 acres in size. Overall detention for this development has been accounted for with Lake Arapaho built in Phase I. Proposed improvements within the development are designed using guidelines in the City of College Station's Drainage Policy and Design Standards. Drainage Report Page 3 of 3 Indian Lakes, Phase IX k-----jc INDIAN IAK6S PHASE /X t L., i/ '1\► ..%1........Hwic\s4 i \ LAKE , SEX .`` \�\ i ,/ ARAPAH • c3. N ., )1 ::::::::::„:, ti ,.:::::::::::::::::::.:::::::::::::.::::::::;.:.::::::.. ....:.:.? d .:1:::::: .::::::▪:::::::::...................:::::::::::: P, ACH CREEK LONEX ▪ r ' :•:••:-.-:-.:-:-::.:-:::.::::::.:::::.........::•••••••K• ...• •.:: :...;:. EXHIBIT A if Flood Insurance Brazos CountyRate, Map Excerpt Texas and Incorporated Areas Map Numbers: 48041CO215C N.T.S. Effective Date: July 2, 1992 0No0 (0,- C) U N e- .1 V 15 N L IO' MiOA x OD' N O W 004bj_oC°NN") 0�1 t) OD O `11')O In 1C .- 0011=NNNN! C 471M 00a4c)ooln V CO 0911� - C 1- SZbsc6,mv 0 L O) 44r. 0)10) 9Z1=O)O) O)0) 4 O O 01bar64 � V O0NO0(0 Oil co co o6 C r N)10 C0 N 90 O'-'M 0 LI� Mhh = CJI= n r r r t6 C M O)M o iaX Zb4ocd6cd M V O M M t1J OMM em Q ZI c co m co Oo d d C O N 0 0 �13sn - oo C as W � nry10O 1. ` Y 31•pie° Ev� rn X C O0,N C`7 WI 3 Z A113013A � ' E J] 11Vd 10 O 0 0 O z M srN m LL - M014 113uno e 6000. 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Q iomDDNN m ii W U) = 00000 X re g W > Z LU e m.-.0 L x-_N N f7 v J Q 3 m W N N N r N 7 Q 0 J r J N N N N N U Z O J 0 � _ _ W••-r•O) Z r) OD)-? 0 0 0 7 N W ~ W _ J J z y)W..N �tOO V'CON C N =`4:104110{O 0 0 0 0 0 W Q N L P. c o. Q- 1�n00O) 0 Z��00000 N 0 N N N N O O p_ o C O CO f0 N 1N D) Z a W m'o 0 o 0 0 C V p • O I= `m RM 0 0 0 0 0 0 d oa�rivvU)U) U H w C) Tm3 ;�0000o 0 0 ►CD nr)0) in-a) C F ri v c ui 1n N Q N N 10 oO UUacN 0 au, c 0 .n 0 # 0 0 H ci K W o N > > J 7 7 0 0 EXHIBIT "C-3" TYPICAL FLUME w/CURB CAPACITY Capacity of 6' Concrete Flume 10' Common Area —_ i — : _ _ _ 1 {0.5' r TYPICAL 6' FLUME A/CURB SECTION NTS Calculation for 10' Wide Common Area Area = 6.50 sf n = 0.013 Pw = 11 .12 ft s = 0.6% From Mannings Equation Q= 1 .ng A Rh9a S2 Q= 0.013(6.50) (6.50 ) 131 .49 (0.006) 2 Q= 40.3 cfs Exhibit "C-3" 106200012—DRN.dwg EXHIBIT "C-4" TYPICAL FLUME CAPACITY Capacity of 6' Concrete Flume 6' „,,,,/... r0.5" (min.) VAA TYPICAL 6' FLUME SECTION Calculation for 10' Wide Drainage Esm't. Area = 4.12 sf n = 0.013 Pw = 10.12 ft s = 0.6% From Mannings Equation Q= 1 .499 A Rh 3 S2 Q= 0.613(4 .12) (4.112)3 (0.006) 2 Q= 20.09 cfs Exhibit "C-4" 106200012—DRN.dwg EXHIBIT "C-5" TYPICAL STREET CAPACITY Street capacity of 26' Concrete Streets 10post Q=27.2 cfs 100post Q=40.4 cfs 26' 4:1 rt'a" 4:1 Max. 2% is Water Surface TYPICAL 26' STREET Calculation for 6" Depth of the Cross—Section (One travel lane) Area = 6.08 sf n = 0.013 Pw = 29.1 ft s = 0.7% From Mannings Equation 1 Q= 1 .49 A Rha S2 Q= 0164196.08) (29 8 )3i3 (0.007)2 Q= 20.52 cfs Exhibit "C-5" 106200012—DRN.dwg 1 \ \ \ V \\ �ZZ // _ _ \ \ \ � \\ \\ / J (////// / � \ \ 1 1 \ \ \\ -ii/ I \ \ \ \ \ \ \\\ / 1 / 111 ( / l' \t. _.- \ \ , \ I I I I ) I � � \ � \ \ \ / l ( ( (1/ . ,. \\ , r_ / \ I I I I I \--- • -- \ \ \\\ \ \ \ \ \ \ \ �///// 2 — ! \' ti \ \Ili ---. ___ - ..--- . __-, ..\\, , \ \ ---,:,---„<///1/",�� ,- \\\ 1 , \\,..\ Z /nv \ / 092 /� „I_ _)7\-771vc \ ' ,' D I I f ��`i,--.67, -,%- _ -\„," -- \ It %i >.� / p I \ i / ,� -' __ 2921 _ - ` ''if . -_.�---'1--/i6<�\�. ----__,/\' �\ f // j j -400000-. — • ----,<"65. _ °'=' \��,rlu ,,,,'r -7--- ,. •-_ --1 /// 0 / - - ------ •• .„:: __,_ ______ ih4 -----V -_____ / 1/7/C)_\,,, i / / nti \\\\\\\ \ \ \ 1II �� V o'ti/ \ / . 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